BIOCHEMISTRY A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z                    HOME ABOUT CATEGORIES SITE MAP COPYRIGHT ADVERTISE CONTACT entire Web this site lactose A dissaccharide (12-carbon) sugar that occurs in mammalian milk. It consists of a molecule of glucose and one of galactose joined by a glycosidic bond and is broken down into these simple sugars by the action of the intestinal enzyme lactase. Human milk contains about 6.7% lactose; cows' milk about 4.5% lactose. It exists in milk at body temperature mainly in two tautomeric forms (α and β) in approximately the proportion 2 to 3. People with lactase deficiency have a reduced ability to digest lactose – a condition known as lactose intolerance. In rare cases, lactose intolerance may occur in someone who is not deficient in lactase. Lactose is important in cheese-making, when lactic bacteria turn it into lactic acid, so souring the milk in the production of cheese curd. Related category    • BIOCHEMISTRY Also on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History Transport Concepts & Designs (partner site) BACK TO TOP